An image reading apparatus that controls relative positions of a carriage and a document in a first direction using a motor, so as to read an image of the document on a line by line basis, the carriage being mounted with an image sensor and a light source. The image reading apparatus detects an amount of movement caused by the motor in the first direction and generates a first trigger signal in response to input of a synchronization signal generated in accordance with the detected amount of movement, the first trigger signal instructing to start accumulation of charge in the image sensor, and, after a predetermined amount of time since the synchronization signal used for generating the first trigger signal is input, generates a second trigger signal, the second trigger signal instructing to end accumulation of the charge being accumulated in the image sensor.